1. Field of the Invention
The present invention relates to an improvement of identification mark display means in an electronic board unit in which a leaded/lead-free identification mark, which indicates whether or not the lead content of applied solder is less than a predetermined value, is displayed on a printed circuit board having a circuit component soldered thereon.
2. Description of the Related Art
In order to enhance recycle efficiency in an electronic circuit board having an electronic circuit component mounted and soldered thereon, it has been identified and displayed whether applied solder is a leaded material or a lead-free material.
For example, in Japanese Patent Application Laid-open No. 2009-021486, there is disclosed the kind and shape of an identification mark for visually determining whether each solder on a front surface or aback surface of an electronic circuit board, which includes both reflow solder and flow solder, is lead-free or leaded. On a first surface 10a of an electronic circuit board 10 of FIG. 1 of Japanese Patent Application Laid-open No. 2009-021486, a first identification mark 20c for the reflow solder and a second identification mark 30c for the flow solder are formed, and similarly on a second surface 10b thereof, a first identification mark 20s for the reflow solder and a second identification mark 30s for the flow solder are formed.
The respective identification marks include core portions 25 and 35 having different shapes depending on the difference between the reflow solder and the flow solder and shell portions 21 to 24 and 31 to 34 for expressing the difference in detailed specifications.
Further, the respective identification marks are designed so that solder resist films 26 and 36 are opened to expose an underlying circuit pattern and an outer appearance is changed by applying or not applying a solder paste to the circuit pattern.